Differential flotation concentration of sulfid ores and raw-ore products.



w Jud-CA.

IIEEE'IEFZEAL FILUTJAEEIEH QGE'GEMTZQZAEFEIGH Q15 gUpEEII) GEES Al ll)EAW OIRVE aammum .lfll'ib likewise.

To all "whom may soncom Be is known that L CHARLES Cori-menu? FREEMAN,subject of the Ring f Greet Briteiro and ind, residing" at Wofirems'oreell,

a Broken rlill l lew South Weles, Australia, heve invented. certain. newand useful lioprovements in DifferentialeFlomtion Con.- cenl'rstion ofSullid @res and. Rew- Ore Products, of which the following is a speciisto obtain a dificrentiel float, in h Serene sulfide are raisedseparately,

obtained in the one case do 110E ts hl;e.inshle the other case on whenthe treartroenl'. is identical.

"-cordirq to one method trse smeosof 'po d 1 .--.d solid ore collec'tifloat is firsi, obtained, and this collective float is retri ved byflotation to different-kyle the minerals, SOlElBli-iRWS one mineral andsome- Limos another mineral flea ting in the liquor in preference loother mineral or minerals. In another method the powdered ore is eddirectly to obtain dillerentiul floors, one produiixt and siibsecpienply another due; hem brought up. 1211 all cases the "us lell:wi'lxhl-he residue in the flotspuretus, 5 which control thefllGl-fillfll} o"? not fully recognized, which operate to modnycontrolling factors fully practical. pmposes how lo the ollectiveness an2 the ensure of shoes hull (.le zermiued reenlisere oh wow .querulyreproduced .l no action.

o. rsi dis iuffrwguim lieu-(e it is that specification of LettersPatent. lf gpkgniggfl App, 2?;

,lllfio,

Application filed ll-larch 556, 1.91%. Serial filo. 871,?851

- of unrecognized factors in the process brings about failures llndifferential flotation of mixed lead-zinc sulfids with alkalinecarbonate solutions, it has been found that owing to heretoforeundiscovered causes zinc sulfids are raised in some cases, lead sulfidein other cases, and a. confused float of mixed sulfide obtained in othercases.

So much uncertainty exists as to the 112i ture grade of the productwhich is ohtaiuehle by flotation. separation in alkaline liquorswithout, reagents that, no process is now used in practice which reliesupon the flotation effect in alkaline liquors alone to procure adillerential separation 01- leed sulfids, zinc sulfide, iro sulfide, andgengue, whether the pulp be qore'pulp or pulp consisting of a, mixedconcentrate of lead sulfide and zinc sulfide.

I have conducted an extensive investigation involving many hundreds oftrial separations of mixed sulfide in alkaline carbonate solutions, andmade assays of results therein obtained to discover hitherto unknownfactors which have operated to produce What have appeared to heinconsistent Bileud reversed results obtained in practice,

telzio liquor. l am concerned only with the erenliel" separation ofcomplex S111- lad r Whether from ore pulp or from mixed coocentrates, toobtain. lead sulfide seperolely from Zinc sulfids and iron sul fi ls byegitst'(yo-aeration flotution in 21 oh:- cui'i; liquor eoutoining analkaline oerhonele.

A process has been published according to w ich it is claimed thathleude is preferem lielly floated by ogitatioueeration in a di aqueoussolution of sodium carbonate shes the separation is made more effechyincrease of temperature. This proc- Us how-ever produces indiliferent ornegative m rna results in many cases, and the cause of the :failure hasnot been determined llLl'OtOfOiL The process is therefore too unreliablefor practical use and it is not in fact used conimereially.

The investigations made by me non estab lish the heretofore unrecognizedfact that the process above referred to obtains a lloat of blende onlywhen the Zinc iillliltl particles are superficially uietallized. withcertain other metals 9., copper) to a definite etctcut, and that whereonly partial nictallimr tion of the blende has occurred anindiscriminate float is procured. The nietallizio wol the zinc sullidsis the result of electrolytic or other action when copper or a metalelectronegative to copper or a saltol' copper or of such other metalsoluble in" the liquor is in contact with or present in the l'lotatiouliquor. Thatznetallizing' occurs has been established in numerous andanions tests. hen the 'llotation is eli'ectcd in apparatus constructedwholly of iron, or of other metal not electro negative to coppeiu or itcoustructed of Wood, and it also no copper or other metal elcctro-uee'atire to cop )er be present, c. gu nercury or silver (in both casesreferring not only to the metals in the free state, but also compoundsof the said metalsv e. 9., soluble salts of these metals), a dellnitelypreferential action in respect oi lead sulfids is displayed. Thetemperature at which the process is conducted ail'ixzts the rate atwhich separation occurs, as in other flotation separation process sfoppcrii-zas tion of the olende occurs more readily and more completelyat higher than at lower temperatures when the operation conducted incopper apparatus.

The etl'ccts referable to copperizing of the hlende are found displayedwhen the ore is treated in a copper apparatus in the lire-t instance toobtain a. coll .ctiro flea and such collective tic-at is subjected toreliot-ation in a machine of wood,- iron or other inert material toobtain the gralena and hlende sepa rately. In this case it is usuallyfound that. the degree of copperizino insuliicient to endow the lilendewith distinctly better floats able quality than the graleoa. but that itis enough to modify the effect of the liquor so that a greater or lesspropo on of the lands comes up with the galenzh resulting in a more orless confused hnliscriuiinate float. in. all cases however, thecoppcrlning of the blende even when extensive is not enough entlo' thehlende with a very ax alted flotation value when mixed with an excess ofthe g'alena, so that it is always necessary even when the conditions aretavorahle to the raising o'tthe blcnde that, the

operation shall he conducted with care.

' therwise more or less galena will come up with blende and foul theresult.

lilo it is practically never possrliilc to obtain a. preferential hlendefloat direct from ore pulp in an alkaline carbonate solution... unlessindeed positive means for copperizine or otherwise endowiug the blendewith superior fioatable qualities are used, and that has not beensuggested heretofore. Even when copper apparatus is used, the extent ofthe coppcrizing effect is insuilicient to endow the blemle with superiorlloatable qualities. llut it a collective float is first obtained bytreatment, in copper apparatus, and this collective float is subjectedto rellotation in an alkaline carbonate solution, again using cop perapparatus. then in this second operation, the copperizatiou of theblende is sutliciently ompleted and a preferential blends float will heobtained, the bulk of the ga-lena remaining as unlioated residue,

An incidental proof that the hitherto nuohserved copperizing of theblends is the cru- 3 cial factor in this method of treating sull'idpulps had in the fact that if some oil (euc: l vptus oil for instance)such as is usually applied as a trothing agent is added to the pulpbefore contact with copper occurs, the cllects otherwise obtained aredistinctly modified. owing; to the "fact that the filming: of thel)l(l1(l8 with oil inhibits eopperizin o; to a greater or less extent.And the same is the case it a copper salt he added to the liquor. But ita copper salt he added to the liquor before oil is introduced, theblends acquires the lloatahle character due to copperization. (omiersalts unless employed in excessive quantity cannot be touud, hy.theordinary 109 analytical methods in the liquor at the conclusion oi? theoperation, but, their presence with the separated blende can be shownlo}; the usual chemical tests. In the case of petitire l'lotation, whenthe first float is ohtained by any known process in which the liquor isstrongly acid. then not-Withstanding that the blende sull'erscopperizing only in the retrcatnient, a preferential blends lloalwill heobtained, partly owing to the partial 1J3 cta'iperizing ol the blendsand partially to the lea-adenine eli'ect, ot' the acid on the galena. inthis case the galena. is seen to he discolored hy the action of the acidt ereupon. it is tht clear that any h cert existing belief that alkalineliquors alone pro (h a preferential zinc "float from clean .nirixetisullld pulp is entirely erroneous. lllende has beenseparated in fact insect solutions by the agency of copper or other operative factors whichact either to exalt the lloatahle qualities of the blends or "todiminish the lloatahle qualities of the galena. or both.

My object in another mode of operation is to obtain a preferentialfloat, of galena, and l attain this oh ect loy avoiding contact of theoulp with copper and with metals electrenegative to copper and withsalts of said metals which are soluble in the liquor,

"suits in any particular case isreadily ascermortar about 1% to about10%according to the behavior therein of the particular ore orconcentrate under treat1nent.- The appropriate strength to produce mosteffective retainable by laboratory test ona few grams of the ore orconcentrate which is 18 be treated.

- The ore or concentrate to be operated upon should preferably not carryor contain oils or other organic sulfptances; and it is economicallydesirable that it shall not be in an acid condition:

The following are examples of treatment of a variety of pulps accordingto this present process.

In the case of a calciticore, tion liquor containing 2.5% of sodiumcargrought iron vessel at a temperature of 50 -a cording to knownpractice for a. period of about four minuteal obtained afloatzconsisting of 63.2% lead, and 8.6% zinc. A reliotation of this productunder the same conditions yielded a product containing 73% lead and 6.2%zincl The values contained inthe untreated pulp were 15% lead and 9.7%.zinc. The ultimate, diflerential result in favor of lead was thereforein this case approximately ?.6 to 1.

A similar ore plup treated in a copper machine. yielded a concentratecontaining 39.2% lead and 27 .8% zinc. The presence of the copper in themachine therefore destroyed the preferential efi'ect of the flotation,the concentrate obtained having about thesame relative proportions oflead and zinc as the original pulp.

In the case of a rhodonitic ore treated with a similar liquor in awrought iron ves sel at temperature C. for a period oi three minutes,the ore assay being 14.4.- zinc and 14.6 lead, a concentrate wasobtained carrying 65.8% lead and 7.1% zinc, and from this are-concentrate was obtained by' a repetition of the same treatmentcarrying 74.6% lead and l.8% zinc.

A similar ore treated in the same way in a copper vessel yielded a firstconcentrate containing 23.5% lead and 35.8% zinc, while thereconcentrate contained 21.%l% lead and 39% zinc. This is a case inwhich the cop perizing of the blende displayed itself in theretreatment, so that blends. was raised in' preference to galena.

A. silicious ore treated in a similar liquor:

and employing aeration-agitation ac 10.l% lead, yielded a concentratecontaining only 10.2% zinc but 60% lead; while a similar ore subjectedto the same process in a copper vessel produced acoacentrate containing33.4% zinc and 29% lead.

I have also successfully treated collective floats obtained by otherprocesses, so as to obtain galena from thein leaving the blende with theresidue.

An instance of the ineiiicacy of alkaline carbonate flotation to obtainditl'erential re sults is found in the case of the retreatinent of acollective Potter float obtained in iron apparatus and containing; 33.2%Zinc and 27.8% lead. This collective float was" washed and thenretreated in a solution of soda carbonate, in a copper machine, at 50(3., five minutes period of contact and four minutes period ofagitation-aeration being allowed. The float thus obtained consisted of3d.4% zinc and 27.et% lead. these relative proportions of constituentsbeingsubstantially'identical with their relative proportions in thecollective lo-at before retreatment. ln bonate, and conductingtheoperatlonin a this case the nietallizing of the blende was insufticientto produce difi'erential flotation edects. If the retreatrnent had beenconducted in an iron or wooden machine a preferential galena float wouldhave been obtained. A. distinct znetallization would have brought abouta distinct differentiation of products and so procured a preferential.flotation of blende in the alkaline carbonate solution.

v A'reztreatment of a collective float obtained with boiling acid l%sulfuric acid), and containing 31.4% zinc and 27.5% lead, gave onretreatrnent 62.2% lead and 1l;6% zinc, a very substantialdifferentiation in the favor of lead being rocured in this case. The

n qrefiotation was eil ected in a wrought iron in a wrought iron vesselat 59 C. for our minutes, and containing 12.5% zinc and machine with a2.5% solution of carbonate of soda, at temperature 57 (3., with live minutes contact and four minutes aeration-agitation. A. portion o1 the samecollective iioat retreated in a copper machine instead of in an ironmachine as in'the lastnientioned case, producechin consequence of thepartial metallization of the blends, an entirely opposite result, via,15.8% lead and 43.2% zinc. The action of the first acid flotation in thegalena was also displayed in retarding its flotation ih therefiotationstep. The collective float was in each case washed and aerated, in the one case in a wrought iron machine and in the other case ina copper machine, with a very small quantity of sodium sulfid, beforebeing submitted to reliotatiou. The same rule is established for theretreatment of collective floats produced by original treatment in acidliquors with oil.

A collective float ()blfiInQCllll a copper machine with acid andeucalyptus an contained 7 .5'per cent. zinc and 30.9% lead: After the altreatment the collective float was drained, water containing sulfuretedhydrogen added and the pulp allowed to stand therein for thirty minutes.After again draining and agitating in water to expel sul-- fnrctedhydrogen, retreatnient was effected in a. copper vessel with three percent. sodium carbonate, one-tenth of a. pound of eucalyptus oil per tonof ore being added, and the treatn'ient effected at (30 C, with oneminute contact and five minutes aeration agitation. The result; was afloat containing $2.4M; Zinc and 16 lead. This result reprean imperfectdifferentiation, hut evidences the fact that the original and therepeal; treatment in copper machines effected a smiicient copperizationof the hlende to endow the hlende with distinctly iioatahle ipialitiesas against galena. Taking in contrast wiih this another collective floatproduccd by similar acid and oil treatment in a wooden vessel andcontaining; Wat)? Zinc and 33.4% lead, afte intermediate treatment as inthe lasiv liiQiltlOllOd case. repetitive reflotation in a wooden machinein a solution of carbonate of soda, at 52 C, time of treatment twominutes cont'ac't and three minutes aeration-agitation. gave a productcontaining (52.8% lead and 12.4% zinc. The contrast in the reheatproduct thus obtained with that obtained in the last. mcni'ioned case,clearly evidences the fact that the carrying out of the process incopper and wood machines respectively. procurcs an entire reversal. oflhe dil fercntinl effect in respect of galena and hlcnde.

in another case in which the procedure was tliimilar the first'trnitn'ient was carried out in a copper machine and the retreatinen'tin a wooden machilw, with the result that the rcfloated 1' ro 'luct wasa mixed float practically identical in lead and zinc constituents withthe original collective float. in this case a partial metallizinp; ofthe blende occurred. suiilicicnt to disturb the preference which wouldotherwise have been displayed in favor of galena, and the result wasthat hlcnde and gnlcna were brought up together in the reiloa't'.

The same fact has been established in conncclion with the rei'reatnientof collective iloals priiiduced in alkaline liquors with oil,

" at 1% 1s made clear under all circumsic. i'hat. ahsence ofmetallization of the hlendc will result in preferential action of lhainccarbonate solutlons on thegalcna,

hydrogen, soda sulfid, or other reagents for the purpose of procuringcertain definite known effects.

In operating-with alkaline carbonate solutions the addition of oil isunnecessary for {u'omoting flotation of the galena in preference toblende hut galena flotation can he successfully effectednotwithstandingthe presence of some oil. (lil operates to encourage thelifting of hlende with the {53181121, and when this tendency isencouraged unnecessarily, the galena float obtained is fouled with acertain proportion of lolende which in the absence of oil would haveremained with the residues.

The degree of concentration of the solu tion may vary up to 10%, but Ihave usually operated successfully with solutions containing Within 3%of soda carbonate in water. The operation is preferably conducted at amoderate ten'iperature, and the apparatus used is ordinarily constructedof wood or iron. Three to four weights of flotation liquor to eachweight of dry ore or pulp is used. The greater part of the silverpresent is brought up with the galena. The raw orc or mixed concentratesto be operated on is reduced to thatv degree of fineness which isnecessary in order "to mechanically liberate the mineral particles from.the gzang'uc and from each. other. and facilitates flotation; ordinarilyabout mesh is desirable. lhis is the case with eharaeterislcic Brokenl'lill ores. lint in some cases the fineness must approach 5-300 meshand in other cases a coarser mesh than 70 suflices.

The powdered ore or mixed concentrate is pulped in the solution or mayhe milled therein, and the flotation operation is con ducted in anyknown type of notation separation apparatus in which the pulp ismaintained in agitation and air beaten into i energetically for a periodof one minute or more, depending upon the nature of the mar teriaL fiven'unutes or e en more being found necessary in some cases. The productrises to the surface in a froth in the well known manner and isoverflowcd or skimmed or otherwise, removed upon its reaching he Isurface or before it attains the surface. The bulk of the gangue and thehull: of the blends and iron pyrites contents remain as a heavy residuewith the gauges and are removed from the machine continuously or atintervals. The leady concentrate obtained by treatn'ient in this mannermay he further concentrated by a repetition of fhe same treatment. Thehlcnde is obtained from the gangumiron pyrites (if present; and other.residues by submitting the same to rellotation in the same medium. (alesser density of solution sufficing in this case), using a coppermachine and adding a small. proportion of an essential oil or otherknown frothi agent. I have not found it necessary to ply anyconsiderable degree of heat to facilitate the action, which isordinarily effected at atmospheric temperatures and up to say. (30 0. Myprocess is of particular commercial value when the zinc contentpredominates in the ore or mixed concentrate and when removal of ironpyrites is necessary.

- stantially excluding other sulfids from the float, such operationbeing conducted while excluding contact of the flotation bath withmetallic copper and metals electro-negative to copper and also salts ofsaid metals which are soluble in said solution.

2. A process for preferentially separating galena from sulfid ore pulpor concentrates containing iron pyrites, which consists in submittingsaid mixed pulp to agitationaeration in and collecting the float from adilute aqueous solution of an alkaline carbonate, and in such operationfloating one sulfid while substantially excluding other sulfids from thefloat, such operation being conducted while excluding contact of thoflotation bath with metallic, copper and metals electro-n'egative tocopper and also salts of said metals whichare soluble in said solution.

3. In the process of difl'erentially floating galena from sulfid oremixed pulp or mixed concentrates by agitationsaeration in a diluteaqueous solution of an alkaline carbonate, the step of floating a partonly of the sulfids present in the mixture while rohibitin'g contactofsaid ore metal and o the said solution, with copper and with metalselectro-negative to copperand with soluble metallic salts of allsuchmetalsl 4. A process of floating galena from sulfid ore pulp ormixed concentrates, which consists in submitting the same todifferential flotation by aeration-agitation in a dilute aqueoussolution of sodium carbonate in a copper-free apparatus, and preventingcontact of said pulp or concentrate and solution throughout thetreatment with copper and copper salts soluble in said solution.

5. A process of floating galena from mixed material containing-- zincand iron snlfids, which consists in submitting the same to differentialflotation by aeration-a2- excluding zinc float, such selective flotationbeing pen new llililOll in a dilute aqueous solution of sodiu ncarbonate in an apparatusof which the parts coming into contact with thesolution are constructed of materials entirely free from copper and frommetals which are electro-ncgative to copper and while pre ventingcontact of the ore material and of the solution throughout the treatmentwith copper and with copper salts soluble in said solution. I

6. A process for separating galena from. mixed sulfid ore pulp orconcentrates, which consists in submitting said pulp to agitationaeration flotation and collecting the float containing galena butsubstantially free from other metal sulfids, such flotation beinperformed in a dilute aqueous solution or alkaline carbonate, while inthe absence of added oily material, and while excluding from contacttherewith metallic copper and metals electrouiegative to copper and alsosalts of said metals which are soluble in said solution.

7. A process for separating galena from sulfld ore pulp or concentratescontaining iron pyrites, which consists in submitting said pulp toagitation-aeration in and collecting the float from a dilute aqueoussolu- 7 tion of an alkaline carbonate, whereby l galena substantiallyfree from other sulfide is floated, suelroperation being conducted inthe absence of added oily material, and while excluding from contacttherewith metallic copper and metals electro-negative to copper and alsosalts of said metals which. are soluble in said solution.

8. A process for difl'erentially floating galena fromzinc and'ironisulflds, which consists in submitting the same to selectiveflotation of the galena while substantially and iron sulfids from theformed by aeration-agitation in a dn rte aqueous solution of sodiumcarbonate, in an apparatus of which the parts coming into contact withthe solution are constructed of materials entirely free from copper andfrom metals which are electromegative to copper and while preventingcontact of the ore material and of the solution throughout the treatmentwith copper and with copper salts soluble in said i the absence of addedoily material.

In testimony whereof I have aiflxed my signature in presence of twowitnesses.

CHARLES OUTHBERT FREEltlAN.

Witnesses:

H. O. CAMrnELL, W. J. DAVIS.

solution, and while in toe Mill

